JP4340072B2 - Radio wave interception prevention system, radio wave interception prevention method, and wall material - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a radio wave interception prevention system, a radio wave interception prevention method, and a wall material, and more specifically, prevents communication radio waves of a wireless LAN radio device used inside a building from being intercepted outside the building. The present invention relates to a radio wave interception prevention system, a radio wave interception prevention method, and a wall material.
[0002]
[Prior art]
In wireless communication performed inside a building, it is extremely important for security to prevent the interception of radio waves leaking outside the building.
[0003]
For example, when using a wireless LAN in the room of each tenant inside a commercial building, the content of the communication may be radiated to the outside through an opening or wall such as a window due to the nature of the radio wave. May be received maliciously for purposes such as eavesdropping.
[0004]
In order to cope with such a problem, a technique for protecting the confidentiality of a signal leaking to the outside of a building by, for example, a scramble method is conventionally known.
[0005]
For example, in Patent Document 1, a scramble code having a length indicated by a code length is generated for each data packet, the data is scrambled with the generated scramble code, and scrambled data in which the scramble code is arranged at an embedded position is scrambled. Data communication is disclosed in which data is attached to data and the data is encrypted with a common key.
[0006]
Patent Document 2 discloses a data transmitting / receiving apparatus that performs communication by transmitting an interference wave together with a digital modulation wave. According to this technique, when the interference wave transmitted from the omnidirectional antenna together with the digital modulation wave is received from the other side, the interference wave component is canceled out by adding the phase-inversion interference wave.
[0007]
[Patent Document 1]
JP 2002-33728 A
[0008]
[Patent Document 2]
JP 2001-094536 A
[0009]
[Problems to be solved by the invention]
However, it is difficult to say that the confidentiality of communication is sufficiently ensured only by the interception prevention technique using the scramble method as described above. That is, there is a problem that the conventional technology for preventing eavesdropping cannot be a defense means against a malicious expert.
[0010]
Further, in the case of wireless LANs that have been rapidly spreading in recent years, there has been a problem that the number of opportunities for interception increases as the number of places where wireless LAN radios are used increases.
[0011]
Furthermore, when communication is performed by transmitting an interference wave together with a digital modulation wave, each radio device must be provided with means for removing the interference wave. For this reason, there was a problem that the manufacturing cost was high.
[0012]
The present invention has been made in view of such a problem, and an object of the present invention is to provide a radio wave interception prevention system, a radio wave interception prevention method, and a wall material that are significantly improved in confidentiality. is there.
[0013]
[Means for Solving the Problems]
In order to achieve such an object, the invention according to claim 1 is a radio wave interception prevention system, which has directivity inside a building and is transmitted from a radio device used inside the building. A receiving antenna for receiving at least one radio wave, a transmitting antenna installed near the outer wall surface of the building and having directivity outside the building, and a radio wave received by the receiving antenna using scramble modulation And processing means for processing, and radiation means for radiating the radio wave processed by the processing means from the transmitting antenna with an output equivalent to that of the radio wave leaking from the building. .
[0014]
In the present invention, a receiving antenna having directivity is installed inside the building, and a transmitting antenna having directivity is installed outside the building on the outer wall surface of the building. And, after receiving and processing one or more radio waves transmitted by the wireless LAN radio used inside the building with the receiving antenna, processing it, and preventing the interception with the output equivalent to the radio wave leaking from the building Radiates from the transmitting antenna as an interference wave for.
[0015]
As a result, interference with only the wireless receiving device of an external eavesdropper related to the wireless LAN without affecting the wireless device in use indoors and without interfering with communication using other frequencies such as a cellular phone. Give it difficult to intercept. The receiving antenna and the transmitting antenna may be installed on the wall surface or embedded in the wall surface. By setting the output to be equal to the radio wave from the radio leaking from the building, it is not necessary to radiate the radio wave with a large amount of power in order to give interference, thereby realizing power saving.
[0016]
According to a second aspect of the present invention, in the radio wave interception prevention system according to the first aspect, the radiated output of the radio wave radiated from the transmitting antenna is less than or equal to an output required by a law. It is characterized by that.
[0017]
As a result, in the manufacture and sale of a transmitter for causing interference, the procedures for testing conformity with the rules and standards stipulated by the Radio Law become unnecessary. As a result, such a system can be easily realized.
[0018]
According to a third aspect of the present invention, in the radio wave interception prevention system according to the first aspect, the processing means is a wireless device for a wireless LAN.
[0019]
According to a fourth aspect of the present invention, in the radio wave interception prevention system according to the third aspect, the wireless LAN radio device includes a demodulating unit that demodulates the radio wave received by the receiving antenna, and the demodulating unit. And a modulation means for scramble-modulating the radio wave demodulated by.
[0020]
According to the present invention, since a wireless LAN wireless device is used as the processing device and the received wave from the antenna is demodulated and then scrambled, the existing wireless LAN wireless device can be used. As a result, the apparatus can be realized economically.
[0021]
The invention according to claim 5 is the radio wave interception prevention system according to claim 1, wherein the processing means is a device compatible with software radio.
[0022]
According to a sixth aspect of the present invention, in the radio wave interception prevention system according to the fifth aspect of the present invention, the device corresponding to the software defined radio transmits the radio wave received by the receiving antenna to the same demodulation method as the radio device. And a modulation means for modulating the radio wave demodulated by the demodulation means by the same modulation system as the wireless device.
[0023]
In the present invention, software radio compatible equipment is used as the processing device, and the antenna is radiated from the antenna by the same modulation / demodulation method as that of the radio in the building. In this way, by configuring the processing apparatus with a programmable device, it is possible to realize an apparatus that can handle any system by downloading parameters corresponding to the system used indoors from the personal computer to the processing apparatus. More specifically, dedicated processing is used for systems using different frequencies and modulation systems such as IEEE 802.11b using CDMA modulation system in 2.4 GHz band and IEEE 802.11a using OFDM in 5 GHz band. There is no need to prepare equipment.
[0024]
The invention according to claim 7 is the radio wave interception prevention system according to claim 1, wherein the processing means includes a receiving means for receiving a spectrum spread signal, and a signal received by the receiving means. Using detection means for performing quadrature detection, storage means for storing the signal demodulated by the quadrature detection for an arbitrary time length, and a clock extracted from the signal stored by the storage means by the quadrature detection is used. And modulating means for modulating.
[0025]
In the present invention, as a processing device, for example, a signal that has been spread spectrum and received is received as a signal source, and demodulation is performed at the symbol rate of the spread signal by primary demodulation using quadrature detection. Then, a demodulated signal, that is, a demodulated signal that has been spread (hereinafter referred to as “primary demodulated signal”) and a clock signal synchronized with the spread signal are extracted.
[0026]
Next, at least one period of the primary demodulated signal and a length of a multiple of the period are stored in the memory, modulated by the extracted synchronous clock, and radiated from the transmitting antenna. This cycle is changed randomly. As a result, even if the external wireless reception device despreads the demodulated spread spectrum signal, it will repeat the meaningless data from the replica signal repeatedly sent at an integral multiple of the spread signal period. The original signal data cannot be intercepted.
[0027]
The invention according to claim 8 is the radio wave interception prevention system according to claim 1, wherein the processing means includes a receiving means for receiving a spectrum-spread signal, and a signal received by the receiving means. A detection means for performing quadrature detection and a signal demodulated by the quadrature detection are passed through a variable delay device that arbitrarily changes the delay amount of the signal with time, and modulation is performed using the clock extracted by the quadrature detection. And modulation means.
[0028]
In the present invention, the processing apparatus receives a signal that has been spread spectrum and emitted. Then, the signal after quadrature detection is passed through a variable delay device whose delay amount changes randomly with time, and then modulated using a clock extracted by quadrature detection of the received signal. Thereby, since the spread spectrum signal intercepted by the external wireless reception device becomes meaningless data, it is possible to prevent the interception.
[0029]
The invention according to claim 9 is the radio wave interception prevention system according to claim 1, wherein the processing means turns off the power when there is no radio wave received by the receiving antenna. To do.
[0030]
Thereby, power saving of a processing apparatus can be performed.
[0031]
The invention according to claim 10 is the radio wave interception prevention system according to claim 1, wherein the receiving antenna and the transmitting antenna are array antennas having a bandwidth of 2 GHz to 5 GHz, and the transmitting antenna is the processing means. The radio wave processed by is radiated with the same directivity as the leaked radio wave from the wireless device.
[0032]
In the present invention, as a receiving antenna and a transmitting antenna, for example, a wideband array antenna whose directivity can be controlled in both 2.4 GHz and 5 GHz bands is used. The processed radio wave is radiated from the transmission antenna with the same directivity as the leaked radio wave from the indoor wireless LAN radio. Thereby, an interference wave can be generated efficiently.
[0033]
The invention according to claim 11 is the radio wave interception prevention system according to claim 1, wherein the processing means is demodulated by the demodulation means for demodulating the radio wave received by the receiving antenna, and the demodulation means. A first processing device that includes a modulation unit that scrambles and modulates a radio wave; and a second processing device that transmits the radio wave received by the reception antenna from the transmission antenna, the first processing device and the The second processing apparatus can be switched by an external signal.
[0034]
In the present invention, the processing device receives a radio wave from a radio inside the building with a receiving antenna, performs scramble modulation, and then transmits a radio wave from the radio inside the building. A second processing device for receiving from the receiving antenna and transmitting from the transmitting antenna is provided. And a 1st processing apparatus and a 2nd processing apparatus are switched by the signal from the outside. Thereby, even if the access point of the wireless LAN is installed in a different room, it can be used with good quality from the wireless LAN terminal.
[0035]
According to a twelfth aspect of the present invention, in the radio wave interception prevention system according to the first aspect, the reception antenna or the transmission antenna is embedded in reinforced concrete.
[0036]
The invention according to claim 13 is the radio wave interception prevention system according to claim 1, wherein the reception antenna or the transmission antenna is embedded in a PCa plate.
[0037]
According to a fourteenth aspect of the present invention, in the radio wave interception prevention system according to the first aspect, the reception antenna or the transmission antenna is formed as a curtain wall.
[0038]
The invention according to claim 15 is the radio wave interception prevention system according to claim 1, wherein the reception antenna or the transmission antenna is embedded in a window sash.
[0039]
According to a sixteenth aspect of the present invention, in the radio wave interception prevention system according to the first aspect, the reception antenna or the transmission antenna is embedded in a door frame.
[0040]
According to a seventeenth aspect of the present invention, in the radio wave interception preventing method, at least one transmitted from a radio device used in the building using a receiving antenna having directivity inside the building. Using a processing device that receives two radio waves and performs scramble modulation, processes the radio waves received by the receiving antenna, and installs the processed radio waves in the vicinity of the outer wall surface of the building. Radiating at a power equivalent to the radio wave from the radio leaking from the building from a transmitting antenna having directivity.
[0041]
As a result, interference with only the wireless receiving device of an external eavesdropper related to the wireless LAN without affecting the wireless device in use indoors and without interfering with communication using other frequencies such as a cellular phone. Give it difficult to intercept. The receiving antenna and the transmitting antenna may be installed on the wall surface or embedded in the wall surface. By setting the output to be equal to the radio wave from the radio leaking from the building, it is not necessary to radiate the radio wave with a large amount of power in order to give interference, thereby realizing power saving.
[0042]
The invention according to claim 18 is a wall material that has directivity inside a building and receives at least one radio wave transmitted from a radio device used inside the building. An antenna, a transmitting antenna installed near the outer wall surface of the building and having directivity on the outside of the building, processing means for processing radio waves received by the receiving antenna using scramble modulation, and the processing means And radiating means for radiating from the transmitting antenna with the output equivalent to the radio wave from the radio device leaking from the building.
[0043]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0044]
(First embodiment)
FIG. 1 is a diagram showing a configuration example of a radio wave interception prevention system according to the present invention. The radio wave interception prevention system shown in FIG. 1 includes a reception antenna A, transmission antennas B1 and B2, a processing device 200, a distributor 110, and a wireless LAN system 300.
[0045]
In the figure, a receiving antenna A is a directional antenna installed on a wall surface, and transmitting antennas B1 and B2 are directional antennas embedded in a wall surface as an array type. The receiving antenna A receives a radio signal transmitted and received indoors. The received radio wave signal is processed by the processing device 200, amplified to a predetermined level, distributed by the distributor 110, and radiated from the transmitting antennas B1 and B2 to the outside of the building. The transmitting antennas B1 and B2 have gain only in the direction outside the building and do not radiate inside the building in the opposite direction.
[0046]
On the other hand, the wireless LAN system 300 includes a server 102 and a client 104 that are used as wireless devices for wireless LAN. Both the server 102 and the client 104 are personal computers that perform wireless communication conforming to IEEE 802.11a. Note that the server 102 and the client 104 are examples of wireless devices used inside the building, and terminals such as mobile phones and PDAs (Personal Digital Assistants) can also be used as wireless devices.
[0047]
FIG. 2 is a block diagram illustrating a configuration example when the processing apparatus according to the present embodiment is applied to a wireless device for wireless LAN. The processing device 200 includes a reception RF unit 201, a frequency converter unit 202, a demodulation unit 204, a disturbance unit 206, a modulation unit 208, a frequency converter unit 209, a transmission RF unit 210, a level detection unit 220, a signal generator (SG) 203, And a power supply unit 230. The radio wave of the wireless LAN wireless device sent from the receiving antenna A is amplified by the reception RF unit 201, frequency-converted by the signal from the signal generator 203 by the frequency converter unit 202, and demodulated by the demodulation unit 204. . The demodulated signal is scrambled by the disturbance unit 206, and then enters the transmission RF unit 210 through the modulation unit 208 and the frequency converter unit 209. The amplification factor of the transmission RF unit 210 is variable and can be adjusted to a predetermined power. The adjusted signal is radiated from the transmitting antennas B1 and B2.
[0048]
Thus, the processing apparatus of the present invention can be applied to an existing wireless LAN radio device. As a result, the apparatus can be realized economically.
[0049]
Next, a specific configuration of the disturbance unit 206 will be described. The disturbance unit 206 processes the radio wave received by the receiving antenna using scramble modulation, and may be configured as shown in FIG. 3, for example. In the figure, the disturbance unit 206 includes a pseudo random signal generator 250 that generates a PN (Pseudo Noise) code. In this case, the disturbance unit 206 performs a scramble operation using the output of the demodulation unit 204 and the signal obtained by modulating the output of the pseudo random signal generator 250 by the modulation unit 207 using the clock obtained from the demodulation unit 204.
[0050]
Moreover, the disturbance part 206 is good also as a structure as shown, for example in FIG. In the figure, the disturbance unit 206 includes a primary demodulation unit 251 and a storage / reproduction unit 252. The primary demodulation unit 251 receives a signal that has been spread spectrum and is emitted as a signal source, and performs demodulation at the symbol rate of the spread signal as primary demodulation by quadrature detection. The storage / reproduction unit 252 stores at least one period of the primary demodulated signal and a length that is a multiple of the period, and reproduces the length.
[0051]
In this case, the primary demodulator 251 extracts a demodulated signal, that is, a primary demodulated signal, and a clock signal synchronized with the spread signal from the received signal. The storage / reproduction unit 252 stores a predetermined period of the primary demodulated signal, reproduces it, and sends it to the modulation unit 253. The modulation unit 253 performs spread modulation on the reproduced primary demodulated signal using the extracted synchronous clock, and radiates it from the antennas B1 and B2. By changing this period at random, the external radio receiving device cannot intercept the data of the original signal and intercepts a replica signal that is repeatedly sent at an integral multiple of the period of the spread signal. For this reason, even if despreading is performed in an attempt to demodulate the intercepted spread spectrum signal, the data becomes meaningless.
[0052]
Furthermore, the disturbance unit 206 may be configured as shown in FIG. In the figure, a disturbance unit 206 includes a primary demodulation unit 261 and a variable delay unit 262 that randomly changes a signal delay amount with time. Here, the variable delay device 262 delays the signal for a specific time (for example, 1 msec) according to the signal length.
[0053]
The primary demodulator 261 receives a signal that has been spread spectrum and is emitted. The primary demodulator 261 performs demodulation at the symbol rate of the spread signal as primary demodulation by quadrature detection, and synchronizes with the primary demodulated signal and the spread signal. The clock signal is extracted. Then, after passing the demodulated signal through the variable delay unit 262, the modulation unit 263 performs spread modulation using the clock extracted by the quadrature detection of the received signal. By performing such processing, the spread spectrum signal intercepted by the external wireless reception device is processed as meaningless data, and thus interception becomes impossible.
[0054]
Returning to FIG. 2 again, the level of the signal of the reception RF unit 201 is detected by the level detection unit 220. When the detected level is less than or equal to the specified value, the control unit (not shown) of the processing apparatus 200 turns off the power from the frequency converter unit 202 to the transmission RF unit 210. Here, in order to start up after the power is turned off, the reception RF unit 201 and the level detection unit 220 are normally or intermittently operated at set time intervals. Then, when the level of the level detection unit 220 becomes equal to or higher than a predetermined value, the disconnected power supply is turned on.
[0055]
FIG. 6 is a diagram illustrating an installation example of a transmission antenna. In the figure, it is assumed that the wireless LAN system is used on the second floor of a building 600. Further, the ceiling and floor portions of the building 600 have a shield structure, and it is assumed that radio waves do not enter from other floors in the vertical direction of the drawing. In addition, a signal wave may leak from the window 302 or the window 303 in the horizontal direction.
[0056]
In general, the attenuation of radio waves passing through a window is about several dB, and even when a special metal film is bonded to this, the radio wave shielding performance is about 30 dB (for example, Maeda and Kato, “Easy to understand wireless LAN”, Ohm 1993). Considering that the dynamic reception performance of radio waves is about 60 to 80 dB, the shielding effect in the building 600 is not sufficient. In general, radio waves leaking from the window are larger than radio waves leaking from the wall surface, so that the transmission antennas B1 and B2 are installed in the vicinity of the respective windows, and the signal waves are radiated by the interference waves with the same directivity. By configuring in this way, it is possible to effectively prevent radio wave interception by the intercept receiver 301.
[0057]
Since the transmission data sent by the interference wave is disturbed and modulated with the same signal as the regular signal, the wireless receiver cannot classify and eliminate the interference wave. Correct data cannot be retrieved and received.
[0058]
The processing apparatus 200 may be configured with a planar circuit. In this case, the film can be attached to a window and attached to a window.
[0059]
Further, the receiving antenna A or the transmitting antennas B1 and B2 can be configured as an antenna box.
[0060]
(Second Embodiment)
FIG. 7 is a block diagram illustrating a configuration example when the processing apparatus according to the present embodiment is applied to a device compatible with software defined radio. As shown in the figure, the processing apparatus 700 digitizes the signal output of the frequency converter unit 202 by the A / D converter 203. Thereafter, the demodulating unit 704, the disturbance unit 706, and the modulating unit 708 perform digital signal processing. That is, the demodulation unit 704, the disturbance unit 706, and the modulation unit 708 have the same functions as the demodulation unit 204, disturbance unit 206, and modulation unit 208 described in the above embodiment, but differ in that they perform digital signal processing. ing.
[0061]
The signal output from the modulation unit 208 is converted into an analog signal by the A / D converter 240 and transmitted from the transmission antennas B1 and B2 via the transmission RF unit 210 from the frequency converter unit 209. In this case, digital modulation is used for modulation / demodulation, so that different modulation schemes can be supported.
[0062]
In this way, by configuring the processing apparatus with a programmable device, it is possible to realize an apparatus that can handle any system by downloading parameters corresponding to the system used indoors from the personal computer to the processing apparatus.
[0063]
(Third embodiment)
Next, referring to FIGS. 8 to 12, a wall on which a receiving antenna or a transmitting antenna (hereinafter simply abbreviated as “antenna”) used in the processing apparatus of the radio wave interception prevention system is mounted. Embodiments, such as materials, will be described. FIG. 8 shows an example of a PCa (precast concrete) board in which an antenna is embedded. PCa 802 is concrete in which the concrete is driven only into the lower end of the reinforcing bar assembled in a three-dimensional truss shape, and the thickness x is about 150 to 200 mm. An antenna 804 having directivity in a predetermined direction is embedded in the PCa 802. The antenna 804 having directivity is realized by providing a reflector. The antenna embedded in this way can be used as a reception antenna or a transmission antenna. By using such a PCa plate as a wall plate in place of the formwork, a building incorporating the radio wave interception prevention system according to the present invention can be realized.
[0064]
FIG. 9 shows an example in which an antenna is mounted on a PCa plate. In the example shown in the figure, a scraper 904 is provided on a PCa plate of about 3 m × 4 m, and an antenna box is installed in the scraper.
[0065]
The reception antenna or the transmission antenna may be formed as a curtain wall. FIG. 10 shows an example in which an antenna is mounted on a metal curtain wall. The curtain wall is a non-bearing wall made of a large panel in which various metal members are combined. By cutting a slot 1004 having a predetermined shape or arrangement on the metal surface 1002, an antenna having directivity can be obtained. . Here, the slot 1004 may be covered with resin through which radio waves can pass.
[0066]
In the case of a glass curtain wall, a metal antenna 1106 can be printed on the glass surface 1104 as shown in FIG.
[0067]
FIG. 12 is a cross-sectional view showing a part of a window sash in which an antenna of a radio wave interception prevention system is incorporated. The window sash 1204 in which the glass 1206 is fitted is installed on the wall 1202 and is configured to be movable in the direction indicated by the arrow. An antenna 1208 having directivity is incorporated in the window sash 1204. In this case, in consideration of weather resistance, a portion in which the antenna 1208 is incorporated may be filled with Teflon (registered trademark) or the like. Needless to say, an antenna can be installed in the door sash as well.
[0068]
Moreover, the place for installing the antenna for the outside may be near the outer wall, and can be installed on the floor, ceiling, or inner wall.
[0069]
The preferred embodiment of the present invention has been described above, but the present invention can be modified in various ways other than the embodiment described above. However, as long as the modification is based on the technical idea described in the claims, the modification is also within the technical scope of the present invention.
[0070]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a radio wave interception prevention system and a radio wave interception prevention method with significantly improved confidentiality.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration example of a radio wave interception prevention system according to the present invention.
FIG. 2 is a block diagram illustrating a configuration example of a processing apparatus according to an embodiment of the present invention.
FIG. 3 is a block diagram illustrating a configuration example of a disturbance unit according to an embodiment of the present invention.
FIG. 4 is a block diagram illustrating a configuration example of a disturbance unit according to an embodiment of the present invention.
FIG. 5 is a block diagram illustrating a configuration example of a disturbance unit according to an embodiment of the present invention.
FIG. 6 is a diagram illustrating an installation example of a transmission antenna according to an embodiment of the present invention.
FIG. 7 is a block diagram illustrating a configuration example of a processing apparatus according to an embodiment of the present invention.
FIG. 8 is a diagram illustrating an example of a PCa plate in which an antenna of a processing apparatus is embedded.
FIG. 9 is a view showing an example in which an antenna used in a processing apparatus according to an embodiment of the present invention is mounted on a PCa plate.
FIG. 10 is a diagram showing an example in which an antenna used in a processing apparatus according to an embodiment of the present invention is mounted on a metal curtain wall.
FIG. 11 is a diagram showing an example in which an antenna used in a processing apparatus according to an embodiment of the present invention is mounted on a glass curtain wall.
FIG. 12 is a diagram showing an example in which an antenna used in a processing apparatus according to an embodiment of the present invention is mounted on a window sash.
[Explanation of symbols]
102 servers
104 clients
110 Distributor
200 Processing equipment
201 Reception RF section
202 Frequency converter
203 Signal generator
204 Demodulator
206 Revolt
207, 208 Modulator
209 Frequency converter
210 Transmission RF unit
220 level detector
230 Power supply
232, 240 A / D converter
250 Pseudorandom signal generator
251 Primary demodulation unit
252 storage unit
253 Modulator
261 Primary demodulation unit
262 Variable delay device
263 Modulator
300 Wireless LAN system
302, 303 windows
600 buildings
700 Processing equipment
704 Demodulator
706 Rebellion
708 modulator
802 PCa
804, 1106, 1208 antenna
902 PCa board
904 Scratching part
1002 Metal surface
1004 slots
1104 Glass surface
1202 wall
1204 Window sash
1206 glass
A receiving antenna
B1, B2 Transmit antenna

Claims (18)

A receiving antenna having directivity inside the building and receiving at least one radio wave transmitted from a radio used inside the building;
A transmission antenna installed near the outer wall surface of the building and having directivity on the outside of the building;
Processing means for processing radio waves received by the receiving antenna using scramble modulation;
A radio wave interception prevention system comprising: radiation means for radiating the radio wave processed by the processing means from the transmitting antenna with an output equivalent to the radio wave from the wireless device leaking from the building. The radio wave interception prevention system according to claim 1, wherein a radiation output of the radio wave radiated from the transmitting antenna is equal to or lower than an output that requires a license defined by law. The radio wave interception prevention system according to claim 1, wherein the processing means is a wireless LAN wireless device. The wireless LAN wireless device is:
Demodulating means for demodulating radio waves received by the receiving antenna;
4. The radio wave interception prevention system according to claim 3, further comprising a modulation unit that scrambles and modulates the radio wave demodulated by the demodulation unit. The radio wave interception prevention system according to claim 1, wherein the processing means is a device compatible with software radio. The device corresponding to the software defined radio is
Demodulating means for demodulating radio waves received by the receiving antenna by the same demodulation method as the wireless device;
6. The radio wave interception prevention system according to claim 5, further comprising a modulation unit that modulates the radio wave demodulated by the demodulation unit using the same modulation method as that of the wireless device. The processing means includes
Receiving means for receiving a spread spectrum signal;
Detecting means for performing quadrature detection of the signal received by the receiving means;
Storage means for storing a signal demodulated by the quadrature detection for an arbitrary time length;
The radio wave interception prevention system according to claim 1, further comprising: a modulation unit that modulates the signal stored by the storage unit using a clock extracted by the quadrature detection. The processing means includes
Receiving means for receiving a spread spectrum signal;
Detecting means for performing quadrature detection of the signal received by the receiving means;
Modulation means for modulating the signal demodulated by the quadrature detection using a clock extracted by the quadrature detection through a variable delay device that arbitrarily changes the delay amount of the signal with time. The radio wave interception prevention system according to claim 1. The radio wave interception prevention system according to claim 1, wherein the processing means turns off the power supply when there is no radio wave received by the receiving antenna. The receiving antenna and the transmitting antenna are array antennas having a bandwidth of 2 GHz to 5 GHz, and the transmitting antenna radiates a radio wave processed by the processing means with the same directivity as a leaked radio wave from the radio device. The radio wave interception prevention system according to claim 1. The processing means includes
A first processing device including demodulating means for demodulating the radio wave received by the receiving antenna; and modulating means for scramble modulating the radio wave demodulated by the demodulating means;
A second processing device that transmits the radio wave received by the reception antenna from the transmission antenna, and the first processing device and the second processing device can be switched by an external signal. The radio wave interception prevention system according to claim 1, wherein The radio wave interception prevention system according to claim 1, wherein the reception antenna or the transmission antenna is embedded in reinforced concrete. The radio wave interception prevention system according to claim 1, wherein the reception antenna or the transmission antenna is embedded in a PCa plate. The radio wave interception prevention system according to claim 1, wherein the reception antenna or the transmission antenna is formed as a curtain wall. The radio wave interception prevention system according to claim 1, wherein the reception antenna or the transmission antenna is embedded in a window sash. 2. The radio wave interception prevention system according to claim 1, wherein the reception antenna or the transmission antenna is embedded in a door frame. Using a directional receiving antenna inside the building, receiving at least one radio wave transmitted from a radio device used inside the building,
Using a processing device that performs scramble modulation, process the radio wave received by the receiving antenna,
The processed radio wave is installed near the outer wall surface of the building and radiates at a power equivalent to the radio wave from the radio leaking from the building from a transmitting antenna having directivity outside the building. A method for preventing the interception of radio waves, characterized by A receiving antenna having directivity inside the building and receiving at least one radio wave transmitted from a radio device used inside the building, and installed near the outer wall surface of the building, A transmitting antenna having directivity, processing means for processing radio waves received by the receiving antenna using scramble modulation, and radio waves from the radio device leaking the radio waves processed by the processing means from the building And a radiating means for radiating from the transmitting antenna with an output equivalent to the above.

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